<!doctype html>
<html>

<head>
	<meta charset="utf-8">
	<title>无标题文档</title>
</head>
<style type="text/css">
	.left {
		width: 30%;
		float: left;
		background-color: #090
	}

	.right {
		width: 70%;
		background-color: #F00;
	}

	.content {
		overflow: hidden;
		height: 400px;

	}
</style>

<body>
	<div class="content">
		<div class="left">1</div>
		<div class="right">2</div>
	</div>

</body>

</html>